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Refraction and Total Internal Reflection

https://www.liacoseducationalmedia.com Shedding Light on Refraction (and Total Internal Reflection) is the fourth video in the ground-breaking Shedding Light series of educational science videos. It looks into every aspect of refraction and total internal reflection, giving students a thorough grounding in these two topics. The video comes in five parts and includes two bonus features. In Part A we introduce students to refraction. We explain that refraction is the changing of a light beam's direction when it passes from one material to another. It occurs because light travels at different speeds in different substances. In Part B, students learn about refractive index and we show them, using water and perspex as examples, how the refractive index of different materials affects how much a light beam will refract. In Part C, we show students how refraction affects the way we see things. If light changes direction on its way from an object to our eyes, then the object appears to be in a different position to where it really is. We take a look at spear fishing, explain why things appear distorted when they're partially submerged and take a snorkeler's-eye view at the way refraction changes the appearance of things when we see them underwater. Here's a quick excerpt. In Part D, we explore the topic of Total Internal Reflection. If light is moving from a substance with a higher refractive index into a substance with a lower refractive index, and the incident angle is larger than what we call the critical angle, the light doesn't exit the first substance but undergoes what is called total internal reflection. The internal surface becomes mirror like, even though it's normally transparent. Total Internal Reflection is not just a scientific curiosity. In Part E, we look at how total internal reflection has been put to good use. We shine some light onto reflectors to show how they work, look into a periscope so to speak, and explain how a girl's best friend gets its sparkle. We also look into, or up to, rainbows. Part E finishes with a look at optical fibres: what they are, how they're used, and how they work. In the two Bonus Features, which have been made with more advanced students in mind, we shed some light on the mathematics of refraction, explaining how the Law of Refraction, often called Snell's Law, is derived. We also use the Law of Refraction to calculate the critical angle. Like all our videos, Shedding Light on Refraction comes with excellent teacher notes and outstanding worksheets and practical activities which really help students to fully understand what they've seen in the video. They don't just watch a video, they learn by doing. Visit LiacosEducationalMedia.com for more information about Shedding Light on Refraction and the Shedding Light series. Credits: Liacos Educational Media acknowledges the people/companies listed below. They have all been credited in the Credits of the video as well, and in the program's Teacher Notes file at http://www.liacoseducationalmedia.com.... Thanks to AFC Group (Australian Fibreoptic Communications) (http://www.afcgroup.com.au/). Right Bronchial Tree.ogg (http://commons.wikimedia.org/wiki/Fil...) by http://www.pneumevah.gr is licensed under CC BY-SA 3.0. Iatrogenic-post-intubation-tracheal-rupture-treated-conservatively-without-intubation-a-case-report-1757-1626-1-259-S1.ogv (http://commons.wikimedia.org/wiki/Fil...) by Prunet B, Lacroix G, Asencio Y, Cathelinaud O, Avaro J, Goutorbe P is licensed under CC BY 2.0. Clip Art by Microsoft. Image of the Earth created by NASA. Written, directed and presented by Spiro Liacos. Produced by Liacos Educational Media (http://www.liacoseducationalmedia.com).